WASHINGTON — NASA has pushed back a widely anticipated decision on the design of its Asteroid Redirect Mission (ARM) until January as it seeks to understand if the technology offered by one option is worth its additional complexity and cost.
NASA Associate Administrator Robert Lightfoot said in a Dec. 17 media teleconference that, after briefings the previous day by teams working on two ARM concepts, he needed more information before deciding between them.
“I expected to make a decision today,” he said. “We really got to the point where I needed to get some more clarification on some areas.” He added that NASA Administrator Charles Bolden agreed with Lightfoot’s decision to ask the teams to look into additional details about their concepts.
NASA is considering two options for ARM. In one approach, called simply Option A, a robotic spacecraft would shift the orbit of a small near Earth asteroid, up to ten meters in diameter, into an orbit around the Moon. The alternative, Option B, would use a robotic spacecraft to grab a boulder a few meters across from a larger asteroid and move that into lunar orbit.
In both cases, the asteroid would arrive into lunar orbit in the mid-2020s. An Orion spacecraft, launched on a Space Launch System rocket, would then fly to the captured asteroid. Astronauts would spend several days studying the asteroid, including performing spacewalks to collect samples, before returning to Earth.
The two options were closely matched, Lightfoot said. In the call with reporters, he said an independent review team assessed the options and found them effectively tied. “It was just close,” he said. “We needed more information in a couple of areas to make sure we were making the right call here.”
However, Lightfoot suggested a slight preference for Option B, based on the technologies it offers that can be used for future human exploration missions. “It demonstrates a lot more of the technologies that we need,” he said.
Those technologies, though, bring with them additional complexity in the design of a spacecraft that would land on an asteroid, grapple a boulder, and then lift it off the asteroid. “It’s the balance between the complexity of that particular part of the mission versus the reward for exercising those technologies” that he said that will be the subject of additional study over the next few weeks.
Option B is also about $100 million more expensive than Option A, Lightfoot said. “That’s the discussion we have to have: if I was to go one way or another, what do I get for that $100 million?” he said.
Lightfoot did not disclose the specific costs of the two options, but said both were less than the goal they had set of $1.25 billion, plus the cost of the launch of the robotic mission. Launch vehicles being considered for the robotic mission include the SLS, Delta 4 Heavy, and Falcon Heavy. NASA plans to perform an independent cost assessment of the selected option before a mission concept review in late February.
Lightfoot said he anticipated the additional studies of the two options would take two to three weeks, allowing him to make a decision in January. That should not affect the long-term schedule for the mission, he said, although it may cause the mission concept review to be delayed slightly.
“It’s two or three weeks well spent for the teams to bring back some clarifications around a couple of areas we want to understand more,” he said of the additional studies. “Taking two or three weeks now is not going to change the overall schedule.”